text:
Considering all US untowered airports, what is the furthest distance that E2 airspace (dashed magneta line) projects from the airport?
Considering all US untowered airports (50 states), what is the furthest distance that E2 airspace (dashed magneta line) projects from the airport for which it is designated?
Measure from the middle of the airport, or if the airspace is officially defined from a navaid or other feature that lies on the airport, measure from that navaid.
Example of E2 airspace -- KONP-- http://vfrmap.com/?type=vfrc&lat=44.580&lon=-124.058&zoom=10
On this airport, only the inner circle is E2 airspace.  The outer projections are E4 and don't count for this question-- http://vfrmap.com/?type=vfrc&lat=38.894&lon=-119.995&zoom=10
Beware these 3 airspaces, they are special anomalies, they appear to be all E2 but the projections are actually E4 (see related question Why are KACV and KTLV depicted differently on sectional charts than KSGU, KBIH, and KTPL, even though each is E2 w/ E4 extensions? ).  To my knowledge these are the only 3 of this kind:
KSGU -- St. George Regional Airport, UT -- http://vfrmap.com/?type=vfrc&lat=37.036&lon=-113.510&zoom=10
KBIH -- Bishop Airport, Bishop CA -- http://vfrmap.com/?type=vfrc&lat=37.373&lon=-118.364&zoom=10
KTPL -- Temple, Draughon-Miller Central Texas Regional Airport, TX -- http://vfrmap.com/?type=vfrc&lat=31.152&lon=-97.408&zoom=10
Except for these three anomalies, you can generally assume that a dashed magenta line surrounding the airport whose approaches it protects, with no inner dashed magenta line, denotes E2 airspace.
Don't be shy about posting the longest answer you've found -- if someone else posts longer no big deal.
Give you best guestimate by measuring on sectional, or check this document for the actual airspace description-- E2 airspaces are listed on pages E-2 through E-141 and have "E2" in the heading, like this:
"ANM OR E2 Newport, OR
Newport Municipal Airport, OR
 (lat. 44°34'49"N., long. 124°03'28"W.)
Newport VORTAC
 (lat. 44°34'31"N., long. 124°03'38"W.)
Within a 4-mile radius of the Newport Municipal Airport, and within 3.5 miles each side of the Newport VORTAC 357° radial extending from the 4-mile radius to 7.9 miles north of
the VORTAC."
In any case of doubt, use the document linked above to definitively determine for which airport the E2 airspace in question has been designated.
State whether measuring in nautical miles or statute miles
The document above uses nautical miles (p. A-2).

I'm not complaining because lord knows I've asked some pretty niche questions myself, but is there a reason for this question?

I've been interested in trying to understand airspace design-- why are airports surrounded by such extensive areas of class-E-to-surface airspace-- don't the nearby Class E floors of 1200' AGL or 700' AGL adequately protect the instrument approaches for much of this airspace?  So, an example of an extreme case was desired.  I've marked the question as answered.  Note that such a large block of E2 airspace is quite an impediment to ultralight aviation-- https://aviation.stackexchange.com/questions/35297/which-parts-of-class-e-airspace-can-an-ultralight-part-103-fly-in-without-prio

At the time the question was asked, I didn't know the answer, but then I went through this document https://www.faa.gov/documentLibrary/media/Order/JO_7400.11C.pdf and looked at all the E2 airspace descriptions so I believe the answer given is the correct one.

A related question could be asked, asking why the E2 airspace at Sheridan is so extensive

The paragraph beginning "In case of any doubt" should be modified to include a description of this document and a link to it-- the FAA's "Airspace Designations and Reporting Points" document Order 7400.11C ( https://www.faa.gov/documentLibrary/media/Order/JO_7400.11C.pdf ).  I thought that I had referenced that document earlier in the question, but I didn't.

Best candidate so far--
Sheridan County Airport-- Sheridan, Wyoming-- KSHR
Page E-92 in the "Airspace Designations" document
The E-2 airspace extends 17.6 (nautical) miles southeast of the airport-- and also 16 miles northwest of the airport  -- last amended 5/31/12
http://vfrmap.com/?type=vfrc&lat=44.769&lon=-106.980&zoom=10

As an aside, the US airport with the most extensive area of E4 airspace in terms of surface area appears to be Casper WY.  This could be the subject of another question/ answer.  http://vfrmap.com/?type=vfrc&lat=42.906&lon=-106.464&zoom=10

This answer could be modified to reflect that it based on thoroughly going through this document faa.gov/documentLibrary/media/Order/JO_7400.11C.pdf and looking at all the E2 airspace descriptions, so it is probably the correct one.


text:
Why are the trailing edges of wings not always made as 'sharp' as possible?
I noticed that wing trailing edges of new airliners like A220 (CSeries) are not completely sharp. Instead, they are blunt. I always thought that the sharper the better in subsonic flow. What is the advantage in having this aerodynamic refinement? Is it perhaps to reduce drag or noise?

Making a perfectly sharp trailing edge has two main limitations.
The first limitation is due to the manufacturing process: the trailing edge is where the structural panels of the upper and lower wing surface meet and you need some thickness in the panel to get a proper bond.
The other limitation is aerodynamic: from an aerodynamic point of view, what makes the trailing edge thick is not its physical geometry but the thickness of the boundary layer. Indeed, the "real" aerodynamic shape of an airfoil is the one given by the "sum" of its geometrical shape and the boundary layer's shape. The following picture, taken from this paper, nicely depicts the boundary layer thickness by the trailing edge:

For a jetliner, the boundary layer thickness can go from some 1 to 10% of the chord, depending on the flight conditions (speed, density, angle of attack, shock waves,...). For example, for a jetliner with about a 5 m chord, the boundary layer has a thickness of some tens of centimetres and this is the real aerodynamic trailing edge thickness. So, those couple of mm of the geometrical trailing edge do not matter that much.

Although @sophit's answer is basically correct, I'd look at things a little bit differently.
From a purely structural viewpoint, you'd really prefer that your aircraft was spherical. This minimizes the amount of skin material you need for a given volume, thus generally minimizing weight. It also minimizes or eliminates all sorts of structural difficulties--point loading, lever arms, stress risers, and so on.
From a purely aerodynamic viewpoint, you'd like the trailing edge of the wing to be absolutely razor sharp--something like a single atom thick would be your real ideal. But even if it's thin, material for a sharp trailing edge weighs more than material that simply isn't present.
So the question becomes one of overall design: where do you lose more from extra weight of material to get a sharp trailing edge, than you gain from a small improvement in aerodynamics?
To be honest, I'm pretty sure for quite a while most designers never really gave much thought to things like blunting the trailing edge. First you optimized an airfoil, then you figured out how to build that as efficiently as possible. There was work put into things like modifying the airfoil a little next to engine nacelles, as needed to meet structural requirements, and to deal with changes in airflow near the engines. But most of the design was done somewhat piecemeal: design and optimize one part, then design the next, and so on, until everything was done. But unless a really serious problem arose in a later stage, you did your best to avoid modifying work that was already done.
Now we have (among other things) enough more computer power available that it's relatively reasonable to devote extra time and effort to optimizing on a more holistic scale. So even after we decided on the basic airfoil shape, it's pretty easy to go back and compute weight savings vs. drag loss from having a sharper/blunter trailing edge, rather than treating the airfoil as 100% fixed, and just figuring out the most efficient way to fabricate it exactly as it was originally designed.

for transsonic aerodynamics a structure that grows thicker at the trailing edge can be beneficial.

@PeterKämpf: Yeah, since they mentioned airliners, I assumed they'd only care about subsonic aerodynamics. But yeah, transsonic aerodynamics get weird.

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text:
Why isn't Vy lower than the speeds for best L/D ratio and best glide ratio in an airplane with a piston engine and a variable-speed prop?
This answer to a related question implies that if the power available were constant regardless of airspeed, Vy would occur at approximately the angle-of-attack that yields the minimum sink rate with power idle, which occurs near the airspeed for the max ratio of lift coefficient cubed / drag coefficient squared, slower than the airspeed for max L/D ratio.  The airspeed for best glide ratio should be only a little slower than the airspeed for max L/D ratio, to minimize the extra drag from the stationary or windmilling prop.
Therefore it would seem that in an aircraft with a piston engine and a constant-speed propeller, Vy should be slower than the best glide speed.  Yet this manual for a Cessna 182 gives the best glide speed as 70 KIAS, and gives Vy as 78 KIAS at sea level and 72 KIAS at 10,000' MSL (page 4-14.)  So why is Vy faster than the best glide speed in this aircraft?  Why isn't Vy slower than the best glide speed?
In essence, this is a question about what the power-available curve looks like for an aircraft with a piston engine and a variable-speed prop, plus a question about what other factors may be at play here.
Is less power available at lower airspeed?  If so, does that imply that less manifold pressure is available at lower airspeed?  Presumably the throttle would be fully open in a climb at Vy -- is the engine unable to turn at the optimum RPM for maximum power when climbing at Vy?
Does the answer have to do with the fact that even with a constant speed prop, at most airspeeds, the pilot cannot simultaneously optimize the RPM of the engine and the angle-of-attack of the prop?  And thus the power available (given that RPM and manifold pressure are kept within safe limits) is not constant as the airspeed varies?  Since there is no variable transmission (variable gearing) between the engine and the prop, it would seem that this would be an accurate description of the situation.
(Naturally, the designer of the prop can simultaneously optimize the angle-of-attack of the prop and the RPM of the engine by selecting the appropriate prop diameter, chord width, blade twist, etc, but it would seem that this optimization might be only valid at one particular airspeed, even with a variable-pitch or constant-rpm prop.)
It would seem that in an aircraft like a Cessna 182, the maximum achievable steady-state climb angle would be shallow enough that the "unloading" of the wing during the climb is not very significant, so that essentially the same correlation between angle-of-attack and airspeed exists in climb, horizontal flight, and gliding flight.
Here are some other related ASE questions and answers--
Why is best angle/rate of climb indicated in airspeed? -- informative, but it is unclear whether the graphs are meant to represent the case of a fixed-pitch prop or a variable-speed prop.
Does a windmilling propeller create more drag than a stopped propeller in an engine out scenario? -- informative, but it is unclear whether the "best glide" airspeed in a typical pilot's operating handbook would represent a stopped prop or a windmilling prop.
Is Vy closer to Vbg with a variable pitch prop -- closely related to the current question, but the actual body of the question is phrased entirely in terms of a fixed-pitch prop.

There is a question with a closely related title but the body of the question is actually entirely about fixed-pitch props, so this is not a duplicate of that question.

It's because climbing at Vy the engine only has to overcome the airframe drag minus the prop, on top of the thrust lift component reduction in induced drag you mentioned in your answer to another post.
It's as if you took the prop off and towed the plane with a tow line glider style (this was done on a Wittman Tailwind back in the early 60s for some gliding drag studies to learn the plane's true L/D, with the tow line connected to the engine prop hub; the Tailwind turned out to be an extremely efficient airplane, square corners, stubby little wings and all).
Best glide has to take into account the substantial drag of the windmilling prop, so the best L/D is achieved at a lower speed.  I'm pretty sure the POH numbers are based on the worst case of the prop windmilling at flat pitch (where it goes if you are climbing at Max RPM and the engine quits), where the drag is so massive it's like you deployed a speed brake.
You can improve this a lot by pulling the prop to Min RPM when the power is removed to try to get the governor to drive the blades to full coarse pitch. This gets you at least part way to being feathered, and helps quite a lot in the glide.

Any response to added paragraph "Does the answer have to do with the fact that even with a constant speed prop, we cannot simultaneously optimize the RPM of the engine and the angle-of-attack of the prop?  And thus the power available is not constant as the airspeed varies?"?

It's mostly that the drag of the prop impacts gliding L/D whether or not it's CS for not.  In the climb case, if you have a climb optimized fixed pitch prop, you end up with more or less the same thrust HP available as with the CS.  If it's a cruse prop, you have less than the CS in the climb.  Also yes, you'd think the CS prop's thrust availability is a lot flatter than the fixed one, but there is still a curve with an optimum efficiency range due to variations in blade efficiency with pitch angle.

Eventually that comment (except perhaps for first sentence which is summing things that were already stated in answer) ought be added as final paragraph in answer; it definitely adds to the answer.

As an aside, I know someone who towed a Cessna 182 in the same manner as you describe, with another Cessna 182.  But the purpose was for relocation for repairs rather than for aerodynamic studies.

@John K your excellent answer implies Vbg (Best distance) would be even higher were it not for the prop drag.  This is consistent with using the "thrust" of gravity to move the plane forward at a higher speed and lower AOA.  Using the wing to "climb" out of Vmin sink rate line of flight.  Using thrust to climb seems more Vx to me, and does not seem to work as well.

Yes the prop's effect as an air brake is massive. The Pilatus PC-12 has an LD of 16, up in airliner and low grade motor glider territory, due to a clean design but largely because it has a feathering prop (you wouldn't want a turboprop to be free to windmill).  Vx and Vbg are actually the same speed, 110 kt  IIRC, and best rate is only 10 kt higher at 120.

@John K these numbers are more consistent Vmin sink and Vbg in gliders showing: Vx is slower in fixed pitch because thrust is greater at lower speeds. But "only" 10 knots difference in best rate would translate to 19% more lift at the same AOA.  So the plane literally lowers its head to use thrust for more speed.  A little more fuel for the same lift and more distance.  Great info, thanks!

Again that latest comment by John K would seem worth incorporating into the answer. Note that even in that case though, Vy is still above Vbg.  Thinking of asking another question "Considering the actual thrust or power delivered by the prop to the airframe, what do the power-available and thrust-available curves typically look like for piston and turboprop engines, with constant-speed propellers in each case? Feel free to also include piston engines with fixed-pitched props, and pure jets, for comparison."

@JohnK really what it seems like your answer is explaining, is why Vbg would be slower than Vx (which would occur at the best L/D of the airframe alone) in the case where Thrust was invariant with airspeed.  And obviously Vy is always faster than Vx.

@JohnK --  But since power is closer to being constant with airspeed than thrust is, and thrust is nowhere near constant with airspeed,  it would not be impossible for Vy to be near the best Cl cubed/ Cd squared for the airframe alone, well under best L/D speed for the airframe alone, and possibly below the actual best glide speed including prop effects, even if the prop drag effect you described were very significant.  See two comments up about a possible other question to really get to the heart of the matter.

Well, we will come to realize Vx is Vbg, aerodynamicly, because it is more intelligent to use the wing as a propeller until form drag no longer allows it.  With a fixed pitch prop, the lower Vx essentially uses the higher thrust to "helicopter" the plane into more altitude in a shorter distance travelled.  Saving "putting my head down and bulling my way through the air molecules" for the football season, but that is what you do with excess power at Vy.  Note the "downthrust" angle is actually designed to do this, and the nose may even be below the line of flight.  More lift too.

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text:
What is the meaning of "transition area" as used by the FAA? Has the meaning changed over time since the term was introduced?
What is the meaning of "transition area" as used by the FAA?  Does it currently have a specific meaning?  Does the FAA still use the term at all?  Has the meaning changed over time since the term was introduced?  Is it a term that ceased to have a specific official meaning after the September 1993 "alphabet" airspace reclassification?
Additional context:
FAR 71.71 reads--

§ 71.71 Class E airspace. Class E Airspace consists of:
(c) The airspace areas listed as domestic airspace areas in subpart E
  of FAA Order 7400.11D (incorporated by reference, see § 71.1) which
  extend upward from 700 feet or more above the surface of the earth
  when designated in conjunction with an airport for which an approved
  instrument approach procedure has been prescribed, or from 1,200 feet
  or more above the surface of the earth for the purpose of
  transitioning to or from the terminal or en route environment.

Does this suggest that the term "transition area" is best reserved for areas of Class E airspace with a floor at 1200' AGL?
The term "transition area" does not appear in the FAA's "Airspace Designations and Reporting Points" document, current edition Order JO 7400.11D.
As airspace with a 1200' Class E floor has proliferated to cover most of the US, it seems to have become a common practice to use the term "transition area" specifically to refer to areas with a 700' Class E floor that are protecting instrument approaches. Is this really a correct practice?

As per the FAA Procedures for Handling Airspace Matters:

Transitional areas, Class E, are designated to serve terminal and en route aircraft to include helicopter operations such as:
a. Transitioning to/from terminal and en route.
b. Transiting between airways and routes.
c. En route climbs or descents.
d. Holding.
e. Radar vectors.
f. Providing for course changes.
g. When the route under consideration is almost all within existing Class E airspace and small additions would complete the coverage.
NOTE-
The only areas that are normally excluded in the Class E description should be limited to Mexico, Canada, SUA and international airspace. Exclude SUA only when active. Do not exclude Federal Airways or other airspace areas.
h. En route training operations.

Link here.
I don't know that this definition has necessarily "changed", but they apparently thought it needed clarification in 2011.

Before the September 1993 transition to the "alphabet system", "transition area" was used to describe areas where the floor of controlled airspace was higher than the surface, but lower than 14,500 MSL base of the "Continental Control Area", at least in cases where those areas were designated around airports and along approaches to airports, rather than along routes.  Starting in 1963, these areas started appearing on sectional charts, typically with floors at either 1200' AGL or 700' AGL.
(Source to be provided.)
The term appears to have no current official meaning in the eyes of the FAA.  As stated in the question, the term "transition area" does not appear in the FAA's "Airspace Designations and Reporting Points" document, current edition Order JO 7400.11D.  Nor does it appear in the Pilot-Controller Glossary.

Since your "answer" includes phrases such as "would seem", "I seem to recall", "perhaps the term has no real meaning", plus two occurances of "I cannot provide a source" I don't think it is a worthy answer.  I would suggest you roll all your uncertainties into the question.  I can understand coming across a key piece of information and asking a question that you yourself answer to enlighten others, but you aren't adding any value here.  If this was a discussion forum, then maybe...

I agree it is not a great answer at present.  I intend to improve it.  I'll consider rolling some of that content into the question but am not sure it would really improve it.

To be honest, it isn't really an answer at all.  It simply provides amplifying information about your confusion regarding the term, and how it is applied.  Its it a good question, but not a good answer!  ;)

Taken under consideration...


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Why are there double hinge lines on the rudders of the Grumman C-2?
Why are there two sets of hinge lines on the rudders of the Grumman C-2?

A photo from the related ASE question Why does the C-2 left inboard stab not have a rudder?
Why would two hinge lines provide more control authority than just using the forward hinge line and deleting the rear one?
And why was it thought worth the extra complexity and weight to use this feature on this aircraft when so few other aircraft have been designed with this feature?
What other aircraft have been designed with this feature?

So, could we arguably say that this aircraft actually has 10 rudders? (!)  (See the photo linked in question-- )

The double hinged rudder is also a Dehavilland Canada feature on most of its larger designs like the Caribou/Buffalo/Dash 7/Dash 8, where maximum yaw power for a given surface area was a design priority (especially if there are height or other limitations that prevent you from adding more area by going up; in the C-2's case, they also added more surfaces as well to limit height, an obvious issue on a carrier, and the same reason the Constellation had 3 tails).
It improves yaw power for a given overall surface area by allowing the rudder to operate at a larger net angle before significant flow separation, by allowing the airflow to make 2 smaller changes in direction vs one larger change in direction for the same overall displacement.
It's not quite as complicated as it looks.  The trailing edge segment is effectively a giant anti-servo tab and is simply geared to the vertical fin by a push rod.  The actuation system only has to drive the forward segment.  The extra parts and complexity are in the second set of hinges and the actuating rod.  In the C-2 pics you can see the gearing rod attachments in the little blisters. On the DeHavilland Canada products, the gearing rod is hidden at the base of the rudder.

You might want to add that tail height on carrier airplanes is restricted to the height of internal hangars, so the added complexity is the result of strict height limits.

Added some text thanks.  Have you ever seen that sort of thing done on a non-slotted plain wing flap?

The first that comes to mind is the SB-11, but here only the rearmost part is hinged; the rest is sliding out of the wing cavity behind the spar. Since it slides on curved rails, it works like a Fowler flap, increasing camber and chord. Double-hinged flaps without slots are to my knowledge only used on rudders, like on the C-17 or the examples you list.

2 hinge lines will give the rudder more authority because it will direct the air more aggressively. We can think of rudders as vertical and two way extending flaps. It's like the difference between a fowler flap and a split flap. fowler will create a curvature with 2 or more components while split flap only hinges down. Fowler flaps increase the Cl of a wing more than split flap while using low AoA's this makes sense because a vertical stabilizer will not have high AoA.
The fact that C-2 is a naval cargo aircraft means it will be heavy and it will need lots of control authority but it also needs to land on a carrier so it should be small.
One way of increasing yaw control authority is to increase the distance between the empennage and CG hence increasing torque caused by aerodynamic force, the other way is to make the vertical stabilizer and the rudder bigger.
I think the fact that the plane should be controllable while remaining compact, made the designers chose the second option.

Both answers are very good, I took the liberty of editing this: it is not just shortness, but overall compactness in all dimensions that is crucial in navy planes. Hence the double hinges and many small rudders instead of one larger, or one "normal" further back. (Didn't wanna make yet another answer to "compete" here :)

A Fowler flap will also extend the wing chord.

Yeah of course, I was only talking about the curvature. Even if we neglect the extension and only focus on the curvature it comes on the same thing. If we compare cl vs alpha of a cambered and a symmetrical airfoil we can see that the cambered one at 0 AoA has almost the same effect with the symmetrical at 5⁰. So in this case we can say that increasing the camber is definitely better than just using a split surface.


text:
Does the FAA or FCC recommend 123.5 as the preferred frequency for air-to-air and air-to-ground use by glider pilots or balloon pilots?
Does the FAA or FCC recommend 123.5 as the preferred frequency for air-to-air and air-to-ground use by glider pilots or balloon pilots speaking to other glider or balloon pilots or ground support crew, as opposed to the other "aviation support" frequencies, such as 121.95, 122.775, and 122.85?
Context: In the US, what radio frequency or frequencies should be used by glider pilots and balloon pilots for air-to-air and air-to ground communications?

123.300 and 123.500 MHz are recommended by FCC.
FCC 87.323:

The frequencies 121.950, 123.300 and 123.500 MHz are available for
assignment to aviation support stations used for pilot training,
coordination of lighter-than-air aircraft operations, or coordination
of soaring or free ballooning activities.

Applicants for 121.950 MHz
must coordinate their proposal with the appropriate FAA Regional
Spectrum Management Office. The application must specify the FAA
Region notified and the date notified. Applicants for aviation support
land stations may request frequency(ies) based upon their eligibility
although the Commission reserves the right to specify the frequency of
assignment.

Aviation support mobile stations will be assigned 123.300
and 123.500 MHz. However, aviation support mobile stations must
operate only on a noninterference basis to communications between
aircraft and aviation support land stations.

See your related question for soaring example of use. From this other answer, the FAA position for air-to-air communication with aircraft other than gliders and balloons:

The air-to-air frequency is 122.75. Remember that everyone in the air
is using this frequency; transmissions should be kept brief. A balloon
pilot trying to contact a circling airplane would try 122.75 first.

The air-to-air frequency is the common one (122.75 MHz), but extended air-to-air communications for gliders and balloons and coordination with the ground support will be done on 123.300 and 123.500 MHz.
If these answers are not exactly what you wanted to know, tell me so I can complete them.

So it appears that as far as the FAA and FCC are concerned,123.3 and 123.5 are both equally preferable for air-to-air and air-to-ground (and ground-to-air) communications within the soaring and ballooning communities, but the other frequencies I mentioned are not.  Does that about sum it up?

Correct. To me these two frequencies are seen as chat frequencies needed for specific coordination of gliders and manned balloons and their supports (while actual air-to-air for all aircraft is still 122.75 MHz; but communications on 122.75 are expected to be short). I've seen online the use of one frequency as primary and the other as backup, e.g. during competitions.


text:
In what airspace may gliders fly in clouds in the UK without an IFR flight plan and without contacting any air traffic control facility?
In what airspace may gliders (sailplanes) legally be flown in clouds in the UK without an IFR flight plan and without contacting any air traffic control facility?
Also, how high does this class (classes) of airspace typically extend in areas where cloud-flying in gliders is commonly practiced?  (A general range is fine--the intent is to allow the reader to compare and contrast with Class G airspace in the US1, which rarely extends higher than 1200' AGL.)
Footnotes--

Cloud flying in gliders in the US is rare for several reasons, including the fact that the pilot would be required to have an instrument rating in airplanes (see FAR 61.3(e)(3)).

Some other related ASE questions and answers of interest--
Can you fly a glider in a cloud on primary instruments?
Can you fly a glider in a cloud on primary instruments?
Can you fly a glider in a cloud on primary instruments?
"Teaching Instrument Flying"-- Instructor Training Notes-- Dartmoor Gliding Society
"Instrument Flying Training Notes"-- Dartmoor Gliding Society
Cloud Flying endorsement webpage from Motorglide.co.ok

Apparently the question could have been asked much more broadly-- "aircraft" instead of "gliders"-- w/o changing the answer--

Broadly speaking, the UK is Class G, excluding airways and terminal areas, from surface up to FL195.  Can hop in your aircraft and fly IMC without talking to anyone to your heart’s content


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Would FAR 91.227, or any other regulation, forbid use of ADS-B-out in an unregistered ultralight?
In the US, would FAR 91.227, or any other regulation or law, forbid use of ADS-B-out in an unregistered ultralight?  Could the N-number field simply be left blank, without violating any regulation or law?
What about a transponder with no ADS-B-out?
One possibly relevant detail: FAR 91.1(e) exempts ultralight vehicles from all of Part 91.

It looks like using ADS-B without any identifier would be contrary to 47 CFR 87.107(a), which requires all aircraft transmitters (with some exceptions, which don't include ADS-B) to include an identification, usually the registration.

§87.107   Station identification.
(a) Aircraft station. Identify by one of the following means:
(1) Aircraft radio station call sign.
(2) The type of aircraft followed by the characters of the
registration marking (“N” number) of the aircraft, omitting the prefix
letter “N.”
[...]
(3) The FAA assigned radiotelephony designator of the aircraft
operating organization followed by the flight identification number.
(4) An aircraft identification approved by the FAA for use by aircraft
stations participating in an organized flying activity of short
duration.

14 CFR 91.227 does allow for a "TSO-C154c self-assigned temporary 24-bit address" rather than the actual N-number but that part doesn't apply to ultralights anyway. It appears to be a reference to 87.107(a)(4) above.
Transponders are exempt from the requirement to broadcast identification, per 47 CFR 87.107(d).
Based on all that, and unless there's an FAA regulation about it (I couldn't find one), I'd say that a transponder is allowed on an ultralight (if you can operate it within the weight limit) but ADS-B is not.

One other thing to consider - many here are stating that ultralights "aren't" registered. This as I read from the EAA is incorrect.
It is true that ultralights don't register with the FAA, but ultralights can be registered through the voluntary registration system provided by the EAA. More than just issuing a registration number the EAA  states the number should be on the ultralight's tail just like an "N" number. The EAA also states the registration as well should be used when making radio calls. The number however is not an "N" number but instead is an "E" number very similar to the "N" number format. Instead of keying up at a non-towered airfield with "Field name, Ultralight entering down wind for runway xyz, Field name" the pilot would state the ultralights manufacturer such as "Field name, Badland Echo 8743 Alpha Romeo, entering downwind for runway xyz, Field name".
Since there are transponders and ADS-b that are extremely small and even a few that use Bluetooth to connect to a phone or tablet, the question is would this be allowed and can the "E" number be used instead of the "N" number?
Add on to this, if the answer is that this would be allowed or isn't prohibited would an ultralight with such equipment be allowed to file flight plans and request flight following?
With the technology jump over the past 10 years, safety equipment like this has become smaller and cheaper. The same can be said for ultralights which are once again becoming popular because of their low cost. I need to add the the EAA will not just issue an "E" number on request. There are pilot training requirements with a CFI before the EAA will issue the registration. This to me is ideal and similar to how amateur radio operators have been self regulating for years. It's the right direction to go for ultralights since the FAA changed the rules for SLA aircraft and almost killed ultralights.
I can see this voluntary system of registration come into play along with the use of transponders, ADS-b, other safety equipment, allowing flight plan submission, and flight following a major benefit to ultralight pilots looking at upgrading to SLA or PPL. I'm certainly not advocating to allow ultralights to have the current flight restrictions changed. Those limitations should remain, but allowing any type of flying machine to use identification equipment helps everyone in the air as well as those that control airspace.
If you don't think so then I ask the question, why do all with the exception of the very smallest drones (UAV's) need ID systems now, but not ultralights?

"More than just issuing a registration number the EAA states the number should be on the ultralight's tail just like an "N" number."-- I have never heard of anything like this.  Will have to look into it and educate myself.  Thanks for contributing.

One of the required datasets of an ADS-b transmission is it has to have either the aircraft callsign listed on the flight plan, or the aircraft registration number. An ultralight by definition would not have this since all Part 103 ultralights are unregistered. Transponders do not have the same requirements nor dataset transmissions. Although both ADS-b and transponders are even used for ground equipment at airports.
Per 14 CFR Part 91.227

(d) Minimum Broadcast Message Element Set for ADS-B Out. Each aircraft must broadcast the following information, as defined in TSO-C166b or TSO-C154c. The pilot must enter information for message elements listed in paragraphs (d)(7) through (d)(10) of this section during the appropriate phase of flight.
(1) The length and width of the aircraft;
(2) An indication of the aircraft’s latitude and longitude;
(3) An indication of the aircraft’s barometric pressure altitude;
(4) An indication of the aircraft’s velocity;
(5) An indication if TCAS II or ACAS is installed and operating in a mode that can generate resolution advisory alerts;
(6) If an operable TCAS II or ACAS is installed, an indication if a resolution advisory is in effect;
(7) An indication of the Mode 3/A transponder code specified by ATC;
(8) An indication of the aircraft’s call sign that is submitted on the flight plan, or the aircraft’s registration number, except when the pilot has not filed a flight plan, has not requested ATC services, and is using a TSO-C154c self-assigned temporary 24-bit address;
(9) An indication if the flightcrew has identified an emergency, radio communication failure, or unlawful interference;
(10) An indication of the aircraft’s “IDENT” to ATC;
(11) An indication of the aircraft assigned ICAO 24-bit address, except when the pilot has not filed a flight plan, has not requested ATC services, and is using a TSO-C154c self-assigned temporary 24-bit address;
(12) An indication of the aircraft’s emitter category;
(13) An indication of whether an ADS-B In capability is installed;
(14) An indication of the aircraft’s geometric altitude;
(15) An indication of the Navigation Accuracy Category for Position (NACP);
(16) An indication of the Navigation Accuracy Category for Velocity (NACV);
(17) An indication of the Navigation Integrity Category (NIC);
(18) An indication of the System Design Assurance (SDA); and
(19) An indication of the Source Integrity Level (SIL).

But aren't you quoting from something in FAR Part 91?

The bolded paragraph 8 suggests it may have ADS-B and use the temporary self-assigned address, no?

I think this answer would be improved by providing a source for the quoted content--

@Warner Conrad   There does not appear to be a rule or regulation prohibiting it. There just does not seem to be a need for it. You can get authorization to fly into A, B, C, D, and E to the surface for an airport without the transponder or ADS-b. Whether this makes it easier to get authorization is a better question. But, it does not replace the need to get authorization since the aircraft would still be flying under Part 103.


text:
Measurement discrepancy on vfrmap dot com sectional -- is the grid wrong?
At Nome Alaska-- KOME-- the E2 airspace (dashed magenta line) is listed as extending 13.2 (nautical) miles east of the airport-- according to this source page E-9 -- https://www.faa.gov/documentLibrary/media/Order/JO_7400.11C.pdf  --
"Within a 4.1-mile radius of the Nome Airport and within 3.4 miles each side of the Nome
Airport 106° bearing extending from the 4.1-mile radius to 13.2 miles east of the airport..."  'AMENDMENTS 07/07/05 70 FR 22590 (Revised) Corr: 70 FR 33349""
But when I measure on the online sectional chart http://vfrmap.com/?type=vfrc&lat=64.513&lon=-165.444&zoom=10, using the tic marks on the lines of longitude (the lines running north and south) as a scale equal to nautical miles,  the far edge seems to measure more like 15.5 nautical miles from the middle of the airport symbol (as shown by the little blue square) -- now why would that be?  That's about 20% further -- about 2.3 miles different -- not insignificant.
What is going on here?
Is the scale wrong, or is the dashed magenta line shown in the wrong place, or is the airport shown in the wrong place?
I assume "east" in the above usage means "generally east, measuring along the 106-degree radial".
It's not a one-time thing, I'm getting a similar discrepancy with some other similar measurements of other similar regions of Class-E-to-surface airspace, always biased in the same direction.

I just tried it and came as close to 13.2 as I could expect to get.  I even tried going to the furthest NE corner due East and don't get close to 15.5.  I can get shorter than that by going to the little blue square centered on Nome City, but I can't get further than that.  The only way I can stretch it to 15 is if I go to the edge of the blue compass card around the VOR.  So, I'm not sure what you are doing, but it appears correct scale to me...

Measuring from the airport on the left, the one with the big paved runways?  I tried it again too and got no change.

Clearly they are using True bearings/ radials not magnetic but that's not the cause of the discrepancy here

@MichaelHall - I get over 17 miles (tick marks) if I measure from the airport, generally toward the ESE, perpendicular to the far E border of the dashed magenta area, but extend the measurement all the way to the blue compass rose that is centered on the VOR.  I'm truly baffled about what is going on here.

All the clues were there; another member figured it out (see comments).  My computer screen was stretching out the image in the left-right sense, so when I took my nautical miles scale off the tick marks on the north-south line of longitude, and then made an east-west measurement, the measurement ran significantly high.  The question noted I had seen this elsewhere and the fact that that was also on an east-west measurement, but at much lower latitude than Alaska (neither of which were noted in the question), should have been a clue to me as to what was going on.  Nothing to do with high latitudes and nothing to do with errors in the way the airspace or the map grid were charted.
I looked at the same url on a different computer screen and the measurement came out fine.

@MichaelHall good job in figuring this out; sorry for the waste of time!

No worries, I welcome a challenge!  Glad you got it sorted out, that was a puzzling one.  It hit me this morning that a good way to verify any distortion of the aspect ratio would be to measure a perfect circle, (like the VOR ring) in the X and Y axis to check that they are equal North and South.

Now that you mention it I've noticed before when using a MapSource program for downloading GPS traces that circles did not look round; I thought it was an artifact of that program

The sectional map “ticks” and 30 mile grid squares do correspond to nautical miles. The sectional represents a 3D object (the earth) which is roughly a sphere in two dimensions. This is the reason you will find that the left and right edges of the sectional are actually not straight, but curved, and in the US (northern hemisphere)   The bottom (South) part is bigger than the top (North) part because the earth at lower latitudes is larger in diameter than it is at higher latitudes. Measure the sectional with plotting tools, like an E6B with a sectional scale, and you will also find that vertical measurements that go straight north and south (measuring across latitudes) are accurate (due to my above explanation, and the fact that degrees latitude are equidistant from each other at all such points) and that east/west measurements vary drastically as you go up in latitude (further north) because lines of longitude “scrunch together” as you approach the poles. You will find the same with WAC charts in the Southern Hemisphere, except when approaching the South Pole at lower latitudes... the same effect but on the other side of the equator. The error rather nulls out at the equator.
You can even see this curvature in the overview of sectional charts included on the front of each one:
Compare this to the higher latitude Alaska charts:

You can also see the difference in the curvature/shape of the Houston sectional at ~30 degrees north latitude vs the Green Bay sectional just 15 degrees of latitude north of Houston. This is why 2D direct measurements that do not take a 3D great circle into account are always wrong when taken east-west.

I found this when plotting flight plans several years ago and it is an interesting point to realize that when measuring with a scale, it will give you inaccurate distances unless the route of flight is straight north/south. Basically, we cannot measure a segment of a great circle while projecting the 3D earth onto a 2D map with a 2D measuring instrument that doesn’t consider scale variance between latitude and longitude in such a projection.

Thanks but-- surely that can't account for the kind of distortion I'm reporting can it?  Certainly I understand why the ticks on the east-west lines no longer equate to nautical miles when we are far away from the equator, but the ticks on the north-south lines still are good.  But on any given chart, a straight line measured with a ruler is surely a reasonable approximation of a true great circle route, at least on scales of 20 miles or less, isn't it?  Is the deal really just that Nome is so far north that these errors are exaggerated this much?

@quietflyer this error is extremely exaggerated in northern latitudes. The closer you get to the North or South Pole the worse it gets. It sounds pretty reasonable to me from what I’ve seen. This is something I teach my students pilots when training them how to plan cross country flights. One other thing: the sectional is not legal, it is an aid to navigation... the FAA order is. Sometimes things are not perfectly to scale and this happens sometimes. I can’t speak to the website, or as to how they compute measurements, but without using great circle (3D) measurement, the error is unavoidable.

Well-- Nome is pretty far north, but not so far north that the lines of latitude on the sectional don't APPEAR to be straight lines of you lay down a straight edge and check a length on the order of 20 miles, with the projection that they are using.  Lots of useful points in your answer but I'm not convinced that's the whole story here.  My best guess is that it may simply be an error in charting the airspace, maybe they want to err on the conservative side?

@quietflyer for what it’s worth, I just did a great circle measurement on the sectional and it comes out to right at 13.2 nautical miles. Even on short flights (50-60 miles) in lower latitudes, the error is regularly several nautical miles when measuring with a straight edge/scale - and not due to measurement error, but due to the curvature problem. Again, this error at that latitude seems totally reasonable from my experience (I also have a background in GIS and mapping systems :-)

@Pugz, at the small scale of this question I don't think what you are describing is the problem.  Both you and I measured this at 13.2 NM, this has got to be something with the way quiet flyer is making the measurement.  I just cannot figure out what he might be doing...

My understanding is that the chart is a "conformal" projection which means that at any given point on the chart, the east-west scale is the same as the north-south scale.  And the earth's curvature across any given mile along a true great circle path is no greater at high latitude than at low latitude.  I just can't believe that these sorts of issues would cause a 2-mile error along a 13-mile measurement.

@MichaelHall and Pugz-- did you both do these exact steps?  1) Click on second link given in my question.  2) Take piece of paper with square corner.  3) Put corner right in the middle of symbol for KOME which is the magenta circle with 2 runways showing, on the western edge of the yellow Nome area.  4) Align one edge of paper perpendicular to far eastern boundary of dashed magenta shape and make an ink mark where the paper crosses the boundary, right in the middle of the far eastern boundary.  The paper ought to be following the 106 degree radial from the middle of the airport.  (Continuing)

(Continuing) Now move the edge of the paper over to either one of the two north-south lines of longitude that is visible on the map at this scale.  Count how many tick marks between the corner of the paper and the ink mark you drew on the paper.   You'll get between 15 and 16.  Are you really telling me you are doing this and only getting just over 13?

@MichaelHall and Pugz -- Now I repeated the measurement with a Nome sectional downloaded from here--https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/vfr/ -- pdf version -- https://aeronav.faa.gov/content/aeronav/sectional_files/PDFs/Nome_59_P.pdf -- identical result.  It's got to be just an error in the size of the Class-E-to-surface area depicted on the chart.

I am doing it exactly as you describe.  I tired several times to confirm.  Just so add more confirming detail, just now I did it from the runway intersection to the second "0" in the number 700 that is bisected by the Eastern boundry running NNE to SSW.  I then put the corner against latitude 64.5deg N over by Sledge Island and counted down.  4 NM (or ticks) down I come to a magenta line indicating G7.  At 7 ticks down I come to the blue line indicating the OME 242 radial.  3 ticks past that is the heavier double mark indicating 10 ticks.  3 more ticks plus a wee bit and there is my pen mark.

I just downloaded the PDF and tried again, same result.  I can get to 15 only if I go to the blue VOR ring, that's it.  Something just hit me though, what is your screen resolution set at?  If you have a wide monitor that could slew the aspect ratio off enough to account for what you are seeing.  Check that out, or try from a paper copy if you can print one at the proper ratio.

Note sure how to check screen res.  Might have something to do w/ that though.  I did the exact thing you said w/ the 700 number and all that, and I have to keep counting past 13.  I think you've hit on it.  See I was seeing something at an airport in Utah and there too the measurement I was making was mainly an east-west one.

should read "something similar at an airport in Utah"

Down voted as this answer is wrong. The tic marks on the lines of longitude (the lines running north and south) ARE equal to 1 nautical mile. This holds true at any latitude. There is also negligible error on a short route segment like the example given.


text:
How low was this KC-135 near KIAB?
On 5-20-22 a KC-135 passed generally east-bound or northeast-bound near a park in Wichita KS (lat/lon 37.628321 -97.305618) at an unusually low altitude.  Estimated below 2000' AGL.  It may have then landed at nearby KIAB (McConnell Air Force Base) soon after.
This flight path is relatively unusual; normally the tankers fly their patterns on the east side of the KIAB runways, and the stated location is west of the base.
What was the aircraft's actual AGL or MSL altitude when nearest this location?  (Ground level is about 1280' MSL there.)
The time it passed nearest the stated lat/lon was around 5:24-5:26 PM Central Daylight Time.
I tried to research this using FlightAware or FlightRadar24 but I'm not very familiar with how to use these programs to search past data, and I'm not sure whether or not they archive any military data, and if so, whether or not some special method is needed to see it.  So this is basically a question about whether this information is accessible via either of these resources, and if so, how to access it, and what the result is.
Related: Would the "Calibrated Altitude" figure on FlightRadar24 better be termed "pressure altitude"?

As a sidenote, weird patterns and odd altitudes for military aircraft may sometimes stem from commanded mission. Where I live, for example, military pilots are not always bound by standard procedures and limitations. Basic rule was, at least back in the days w/r to minimum altitudes for example "as per flight regulation or as commanded or required by mission".

For military ops trigger could simply be proficiency.

Consider directing answers focussed on whether or not a correction for altimeter setting needs to be applied to the altitude data provided by FlightRadar24, to this related question -- https://aviation.stackexchange.com/questions/93379/would-the-calibrated-altitude-figure-on-flightradar24-better-be-labelled-pres

I think this is what you're looking for:
https://www.flightradar24.com/2022-05-20/22:20/12x/37.62,-97.3/12
Looks like he overflew the field to enter the right downwind for RWY 1 at McConnell AFB at around 2700 ft MSL. That's around 400ft above pattern altitude although I've seen ADS-B readings vary from altimeter readings often. Maybe someone who knows more about that could speak to why that happens. I believe it's because ADS-B does not correct for non standard pressure altitude and this isn't corrected for by the displaying service either (ie. fr24 or fltaware). Curious myself whether there's any way to change that on these services.
Hope this helps

Comments are not for extended discussion; this conversation has been moved to chat.


text:
Why is it common to speak of "Concorde" rather than "the Concorde"?
"Suppose you were researching a book on the history of Boeing B-17."
"Suppose you were researching a book on the history of the Boeing B-17."
Which of those sentences sounds more complete and correct and natural?
Presumably the latter.
Why then, on an hour-long PBS documentary on the Concorde, were people constantly referencing "Concorde" this and "Concorde" that, as opposed to speaking of "the Concorde"?
Check out the "Concorde" tag on ASE for more examples of this practice (as well as some counter-examples).

The Wikipedia article about Concorde confirms that the name is typically used without an indefinite or definite article, at least in British English:

Concorde also acquired an unusual nomenclature for an aircraft. In common usage in the United Kingdom, the type is known as "Concorde" without an article, rather than "the Concorde" or "a Concorde".

The two sources given for this sentence (BBC and British Airways) also consistently use Concorde without an article, but unfortunately they don't explain why.
I remember hearing in a documentary that the British developers omitted the article to highlight how special the aircraft was, but I cannot find a source for that. The closest I found is this Engineering and Technology article:

Unlike almost every other commercial airliner, Concorde sparked such affection that ‘she’ needed no preceding definite article or proceeding marquee number.

So the reason is probably related to how special the aircraft was and how affectionately the people working on the project felt about her.

By the way, in French Concorde is used with an article: le Concorde (see e.g. the French Wikipedia article).

Best answer so far-- if anyone has more info as to "why", keep in mind that the "accept" check mark can always be re-assigned --

Ultimately it was the chosen name for the project and since it was a bi-lingual project the name was used in by both french and english sides working on it (7:40 into the video), as such the Definitive Article is commonly dropped when talking about it. It also derives from the word agreement and prior to the actually aircraft being built everyone was simply working on an undersigned agreement to build a plane.

The name Concorde was chosen as, in both French and English (as
  "Concord"), the word means agreement. The plane was to be called
  Concorde in both France and Britain. However British Prime Minister
  Harold Macmillan, decided to remove the "e" from the end, as he was
  annoyed that his French counterpart, Charles de Gaulle, cancelled a
  meeting with him due to having a cold. The British government's
  Minister for Technology, Tony Benn, later replaced it, claiming that
  the "e" stood for Excellence, England, Europe and the Entente Cordial.

I don't think he was asking "Why was it called Concorde", but rather " We refer to Concorde as just "Concorde" but other planes are referred to the Spitfire, the 747, the SR-71" etc etc.

@sophit Not really. The part of the answer you quoted about the definitive article, simply states that it was dropped, and the question is asking why it was dropped.   The bulk of the answer - and the entirety of the quoted section - is really answering the unasked question "Why was it called Concord/Concorde and why the difference in spelling?"

@sophit Yet we have 'The' Channel Tunnel, 'The' Eurofighter, 'The' Jaguar. I don't think there's any evidence that the 'the' is 'commonly dropped', and even if it were, there's still no explanation as to why in the answer.

@SteveIves: that sounds like an answer, you should post it


text:
Why does the maximum allowable load factor vary with airspeed in some aircraft?
In this ASE answer What is the maximum safe bank angle of a 747?, the author writes:

If we stay with stationary turns (without the "falling out of the sky"
part), the maximum bank angle is given by the maximum load factor of
the 747. At 400 KEAS, this is just 1.5g, so even with the 25° nose
down attitude the maximum bank angle would be 53°. If you fly slightly
slower, the load factor goes to 2g (equals 63° in a 25° descent) and
tops out at 2.5g at 310 KEAS (68.7° in a 25° descent).

Why does the allowable load factor vary with KEAS in this aircraft?
Note that if the wings have any washout, the outboard portions of the wingspan would contribute less to any given total lift force at higher airspeed (lower angle-of-attack) than at lower airspeed (higher angle-of-attack), so for any given G-load, the higher-airspeed situation would seem to impose less upward bending moment on the wing structure.
Is it simply that imposing a drag load makes the wing less capable of absorbing the lifting load?

My immediate thought is high speed buffet limitation (could be either stall or load related) and/or gust limitations.

@JZYL is right. When I wrote the answer, I had buffeting limits in mind. Of course they can be exceeded at the cost of ride quality, but going further into buffeting will also reduce control effectivity. To be precise, the maximum safe load factor depends really on Mach and less on airspeed.
Your comment about washout is correct, and flying higher gs will increase washout from aeroelasticity. But rest assufred that those effects have already been applied when designing the structure for its limit load. Since the calculation was done for an airplane at 30.000 ft, the angle of attack for pulling higher gs is already close to what is needed at low speed and lower altitude.


text:
Why does the surface-level Class E airspace at SIT/PASI (Sitka Alaska) extend so far to the northwest?
The August 1992 Final Rule "Terminal Airspace Reconfiguration" (page 38963, Federal Register Volume 57 No 167, August 27 1992) (link to pdf of entire issue opening to this page) stated that the purpose of "control zones" was as follows:

A control zone ensures that aircraft arriving at an airport under IFR remain within controlled airspace when an instrument approach procedure could put that aircraft within 1000 feet of the surface.  A control zone also ensures that aircraft departing an airport under IFR remain within controlled airspace between the surface and the base of adjacent controlled airspace.

The same Final Rule also makes clear (pp. 38963-38964) that surface level controlled airspace, including surface-level Class E airspace, would serve the same purpose after September 16 1993 as control zones served prior to that time.

With this in mind, why was it necessary to designate such a large area of surface-level Class E airspace at SIT/PASI airport at Sitka, Alaska?  (Pictured above.)  The E4 surface-level Class E "extension" is 12 miles wide, and extends to 28.3 miles northwest of the airport.  (See page E-158 of the "Airspace Designations and Reporting document FAA Order 7400.11F; this airspace was last modified 11-05-2020.)
Is it really true that there are instrument procedures for this airport that could put an aircraft below 1000' AGL in all or most of this airspace?  If so, which procedures are those?
Or does the FAA now designate surface-level controlled airspace based on some criteria other than the one stated above?
Wouldn't an aircraft flying over the Pacific Ocean northwest of the northwest tip of Kruzof Island, inbound for landing at SIT/PASI, flying below 1000' AGL/MSL, be in great danger of colliding with the high terrain (over 2350' MSL) near the northwest tip of Kruzof Island?  Is there really any instrument procedure that could have an aircraft on approach for SIT/PASI below 1000' AGL/MSL at this location?  If not, was there really any reason to extend the "extensions" much beyond the (approx) 2350' MSL terrain near the northwest tip of Kruzof Island?  Based on the criteria stated above, was it really even necessary to extend it that far?
Has the E4 surface-level Class E "extension" in this area simply been sized to to completely contain some particular instrument procedure, regardless of whether or not an aircraft following that procedure might be within 1000' of the terrain (or ocean) in all parts of that "extension"?
Wouldn't much of the airspace covered by the E4 surface-level Class E "extension" extending 28.3 miles northwest of the airport be adequately be protected by a "transition area" with a Class E floor at 700' AGL, or by the existing surrounding Class E airspace floor at 1200' AGL?
This latter, more "conservative" approach would avoid imposing certain restrictions associated with surface-level controlled airspace on various aviation activities, such as the prohibition on VFR flight below a ceiling of 1000' AGL or lower without a Special VFR clearance (FAR 91.155(c)), the requirement for three miles visibility for taking off or landing (FAR 91.155(d)) (consider seaplane operations in this context), the requirement for ½-mile daytime, 1-mile nighttime visibility for part 135 helicopter operations (FAR 135.205(b)), the prohibition on aerobatic flight (FAR 91.303(c)), the prohibition on ultralight aircraft operations without prior authorization (FAR 103.17), the prohibition on Small Unmanned Aircraft operations without prior authorization (FAR 107.41), and more.

FR link may not open to correct page on phone apps.

Of course, the last paragraph re-opens the whole can of worms as to whether those prohibitions really apply in the "extensions" -- see several related ASE questions and answers including https://aviation.stackexchange.com/q/48103/34686 and https://aviation.stackexchange.com/a/86990/34686 and https://aviation.stackexchange.com/q/74738/34686.  Note also that the "extension" is not included in the authorization-required area on the LAANC map for SUAS ("drone*) operations -- https://faa.maps.arcgis.com/apps/webappviewer/index.html?id=9c2e4406710048e19806ebf6a06754ad.

One of these days the FAA is going to have to come out with a truly definitive answer on this, and ideally one that is consistent with the original intent of the circa-1993 rule-making documents--

Considering coastal Alaskan weather, and the huge size of the "extension" area of surface-level Class E airspace currently extending NW of Sitka, would love to hear from someone who actually operates VFR in this area, whether in actual practice the requirement of FAR 91.155(c) to not operate VFR (w/o Special VFR clearance) under a ceiling lower than 1000' AGL in (some forms of?) surface-level Class E airspace is treated as binding throughout the entire Class E "extension" NW of Sitka.  Consider creating an answer to https://aviation.stackexchange.com/q/48103/34686, or drop me a message (chat?)

Just now noticed the irony of a label stating "avoid flight below 1000' AGL", in a surface-level Class E airspace area which is apparently intended specifically to deal with situations where "when an instrument approach procedure could put that aircraft within 1000 feet of the surface."! I assume that when the procedure is flown correctly, the aircraft would remain above 1000' AGL over the sensitive areas--

@757toga -- interestingly, the surface-level Class E airspace is actually having a negative impact on Coast Guard helicopter operations--see https://aviation.stackexchange.com/a/55806/34686

Interesting update to the situation-- https://www.aopa.org/news-and-media/all-news/2022/september/21/faa-shrinks-class-e-surface-area-around-sitka

The LDA/DME RWY 11 approach puts you darned close to 1000 AGL over those mountains if you come in from HEXAB on the localizer - and that assumes you fly it perfectly. The course reversal for that approach is basically smack on top of that 2250 peak.
The airfield itself is basically at sea level (26' MSL), and is on the ocean, so I'd expect there's also some gnarly local air currents fairly regularly, especially for approaches that try to come in between the islands.  That's all pretty rugged terrain over there, and it's got a reputation for having a lot of microclimates.

Good info there, but it still seems that the outer 4 or 5 miles of the area is un-necessary because at that point the plane would be over the ocean--

@quietflyer I expect this is much more about inbound traffic than outbound, and because of the large difference in elevation, they might want to make sure folks are coming in high enough before vectoring them for the localizer?  I'm not sure what kind of traffic they're dealing with normally. It looks like a seasonal airport, so it's probably a feast-or-famine thing

As another answer has noted, the surface-level Class E "extension" to the northwest of SIT/PASI is indeed intended to protect the LDA/DME RWY 11 approach.
In the July 20 2021 edition of the "Airspace Designations and Reporting Points" document, FAA Order 7400.11E, the E4 surface-level Class E "extension" does not exist yet (it would be on page E-160 if it did), and the E2 surface-level Class E airspace only extends 11.1 miles northwest of the airport, extending 3 miles to either side of the 313° radial.
Presumably the LDA/DME RWY 11 approach did not yet exist yet at this time, at least in its present form.
The large E4 surface-level Class E "extension" spanning from 4 miles north
and 8 miles south of the 315° bearing from the airport, extending to 28.3 miles northwest of the airport, was introduced in a Notice of Proposed Rule-Making published May 7 2020, and a Final Rule published July 31 2020, effective November 5 2020.  These rule-making documents do not state what new approach procedure(s), if any, required the protection of this airspace all the way down to the surface.
The NPRM does contain the following text (italics and bolding added):

This action also proposes to establish a Class E airspace area,
designated as an extension to a Class D or Class E surface area, at
the airport. The area would be northwest of the airport and is
designed to contain IFR aircraft descending below 1,000 feet above the
surface.

It does appear that the outer 5 miles of this area would have been adequately served by a Class E "transition area" with a floor at 700' AGL, or even by the existing 1200' AGL Class E floor, because aircraft in the outer 5 miles of this area are over the ocean, not over high terrain.
The subsequent revocation of this large surface-level Class E "extension" has been proposed in a NPRM published February 7, 2022.  This NPRM contains the following text (italics and bolding added):

The Class E surface airspace area northwest of the airport requires
modification to properly contain IFR aircraft descending below 1,000
feet above the surface of the earth. The LDA/DME RWY 11 approach
procedure turn area currently extends 28.3 miles to the northwest, but
the area should be reduced due to the proposed elimination of the
LDA/DME RWY 11 approach procedure turn.

According to this NPRM, the surface-level Class E airspace northwest of the airport will be reduced to an E2 airspace area spanning 1.2 miles each side of the 314° bearing from the airport extending 6 miles northwest of the airport, and an E2 airspace area spanning 1.1 miles each side of the 320° bearing from the airport extending 5.2 miles northwest of the airport.  The E4 "extension" will be entirely removed.
Links:
May 7 2020 NPRM proposing the large E4 "extension" to the northwest of SIT/PASI: Link to text of docket, link to PDF of entire Federal Register issue opening to relevant page
July 31 2020 Final Rule establishing the large E4 "extension" to the northwest of SIT/PASI: Link to text of docket, link to PDF of entire Federal Register issue opening to relevant page
February 7 2022 NPRM proposing elimination of the large E4 "extension" to the northwest of SIT/PASI: Link to text of docket, link to PDF of entire Federal Register issue opening to relevant page


text:
How many nuclear weapons have been lost- and not located or recovered-- from aircraft in crashes or other mishaps?
How many nuclear weapons have been lost- and not located or recovered-- from aircraft in crashes or other mishaps?

I thought wikipedia had a list but closest is https://en.wikipedia.org/wiki/United_States_military_nuclear_incident_terminology#Broken_Arrow_incidents

Short answer, quite a lot but total unclear (and not just for secrecy reasons) - most are due to the US practice of keeping a force of nuclear bombers airborne continuously and/or routinely going on alert to test readyness, at a time when aviation technology was advancing ahead of reliability (see B-36 'six turning four burning'').
General incident lists here and here.  It is challenging to get a clear count of 'lost and not located' for several reasons. In the early era of nuclear equipped bombers it was common for the casing, electronics and conventional explosive 'bomb' to be carried on separate aircraft from the plutonium cores/capsules, or for cores to be in a separate stowage during normal operation. This means that there were several 'nuclear bombs' jettisoned or involved in crashes that were just very very expensive conventional bombs during the incident - many were not 'recovered' because they were mostly high explosive and either deliberately detonated or caught fire. Some of these bombs contained Uranium tampers (Uranium used for density rather than for atomic properties) further complicating the definition of 'lost', finally there are weapons that burned and contaminated the soil (so weapon is lost, material is not).
1956 - B-47 lost in transit to Morocco - carrying two cores but no bombs
1957 - Air to Air missile test - questionable since it was an intended detonation but notable for photo of five people at ground zero
1958 - weapon jettisoned after mid air collision - unclear if core fitted
1958 - B-47 in Morocco burns on ground, contaminated soil returned to US.
1958 - B-47 catches fire on ground in UK while bomb loaded - radioactivity detected by UK teams but US claim no capsule fitted.
1960 - BOMARC missile destroyed by fire - technically not 'lost' since the contaminated area is known and some material recovered during cleanup
1961 - B-52 crash, parts of weapons recovered from marshland but not all.
1965- Mk43 equipped A-4 rolls off carrier deck and not recovered
1966 - B-52 crashes in Spain, two weapons exploded/burned on land, two sank in water. Intact weapons recovered and soil returned to US.
1968 - B-52 crashes and burns in Greenland - soil returned to US for re-processing so not technically 'lost'.
Notably absent from this list is everybody other than the US. UK and France had far fewer weapons, so tended to keep them safe on the ground/prioritize missile delivery though UK did do 'alert' operation so not impossible that a still unreported event happened with the V-bombers. Russia is a more opaque question, but placing more priority on ICBMs over bombers and desire for central control means that far fewer aircraft flew with complete weapons and those that did would have tended to be over land so is statistically possible no USSR/Russian aircraft crashed/were lost while nuclear equipped in a way that prevented recovery. It is unclear if China ever widely deployed nuclear bombs and also tends to operate over land.
If planing to go looking for one, the half life of Plutonium used in weapons is 14 years, so all the weapons in this list (and unknown ones of this era) would no longer be capable of a full nuclear detonation if recovered today. Recovery would still be highly dangerous due toxic materials and unstable explosives.


text:
Why would an airplane with fixed-pitch propeller(s) and no supercharging have manifold pressure gauges? (E.g. Ford Trimotor)
I had recently had a look at the Ford Trimotor NC9645 (link), currently on an EAA-sponsored tour.  The propellers were fixed pitch (possibly adjustable by mechanic on ground), and the engines were not supercharged.  On the instrument panel directly in front of the pilot were manifold pressure gauges for all three engines.  Oil temperature, oil pressure, and RPM gauges for the central engine were nearby on the panel.  The same three gauges for the wing-mounted engines were out on the engine nacelles-- rather difficult to read precisely from the cockpit.
The pilot seemed to fly mainly by reference to the gauges on the panel, only occasionally (at least after warm-up and run-up was completed) checking the gauges on the nacelles.
So, why did this aircraft have manifold pressure gauges for all three engines on the instrument panel in front of the pilot, while other gauges for the wing-mounted engines were mounted on the nacelles?  Is it simply easier for some reason to transmit the manifold pressure over the distance from the engines to the instrument panel, than is the case for the other parameters?  Or is the manifold pressure significantly more useful to the pilot than are the other parameters?
In a non-supercharged aircraft with fixed-pitch props, does the manifold pressure tell the pilot anything useful that an RPM gauge would not?
Am I correct in believing that it's rather uncommon today to have a manifold pressure gauge for an engine with no supercharger and a fixed-pitch prop?  Is this something that used to be more common on aircraft from the earlier days of flight?

A manifold pressure gauge is useful even on an engine with a fixed pitch propeller. It is really just a vacuum gauge as used in many other piston engines.

The MP gauges would be in the cockpit because they are referred to frequently and it's easy to install them remotely with just a hose connecting them to the engines.  Gauges mounted on the nacelles were done to shorten the connections for various reasons, such as to minimize the length of an oil pressure gauge capillary line or a thermocouple wire, as well as save instrument panel space in the cockpit.  This practice was done on airplanes like the Me 110 twin engine fighter as well.
As far as using an MP gauge with fixed pitch props, since horsepower is a calculation involving torque and RPM, if you don't have a torque measurement device on the engine like you do with a turboprop, you can get a decent proxy for torque by measuring manifold pressure.
So on piston aircraft engines, manifold pressure vs RPM is used to calculate horsepower.  Where RPM is controllable independently of torque because of a constant speed propeller, you must have both RPM and a torque or torque proxy measurement to be able to compute horsepower at all.
With a fixed pitch propeller, you can get away without the torque proxy (MP gauge) because RPM varies directly with torque in a fixed relationship and you can estimate horsepower based on RPM in flight.  However, if you want to be more precise, it's still nice to have the torque proxy - manifold pressure - to know the true horsepower being produced at any one time, even though you don't have independent control over RPM.
This is not widely done on GA airplanes with fixed pitch propellers, probably due to cost/complexity reasons, but MP gauges are still nice to have.  My own fixed pitch prop homebuilt airplane has an MP gauge, and it is very handy, as I can know the precise horsepower setting (and therefore fuel burn) at any one time from the MP/RPM being presented, even though I only have control over the MP being set with the throttle. If I was King Of Aviation, I'd decree that all airplanes have MP guages.

RPM tells how fast the engine is turning, manifold pressure (indirectly) how much power it's producing.
If you're in a steep climb, for instance, RPM will drop a little due to loading of the propeller, while in a dive, RPM will rise -- but if the throttle setting is the same for both conditions, manifold pressure will be nearly constant (high RPM will slightly reduce manifold pressure, other factors equal).  Looking at the throttle levers won't quite tell you the same, either -- a number of conditions, notably carburetor icing, can reduce manifold pressure without any change in throttle lever position.
The interaction of RPM and manifold pressure is an important piece of information, especially without head temperature and exhaust gas temperature readings available.

OK, but as the RPM drops in the climb, with fixed throttle position and fixed-pitch prop, surely engine power output decreases as well--  isn't it pretty uncommon to have a manifold pressure gauge on a non-supercharged engine with a fixed-pitch prop?  (Maybe I should make that last sentence part of the question--  )

Re "OK, but as the RPM drops in the climb, with fixed throttle position and fixed-pitch prop, surely engine power output decreases as well"-- we know this even from the simple experience of driving a car up a steep hill; once RPMs start to fall off, you'll probably need to downwshift to keep going-- (did add a couple of sentences to end of question)

The RPM change at reasonable climb and dive angles is pretty small -- a couple hundred RPM out of a couple thousand.  If you're diving steeply enough for RPM to climb a lot, you've got other issues (like overspeeding the engines).

The MP gauge will tell you at a glance if your carb is icing up, by reading greater suction in the manifold at constant throttle setting- telling you that something other than the throttle was restricting airflow through the carb. I wish my old 1973 Subaru had an MP because the induction air preheater on the engine was broken and the carb would ice up regularly after I moved to Oregon and routinely drove through freezing fog conditions.

Interesting info, but in an airplane-- at least if the icing happened during an interval where you were not changing the throttle position, and also were not transitioning from level flight to climb or dive or vice versa-- wouldn't you likely also notice a dropoff of RPMs?

Yes you would, as did I in the subaru. RPM going down, suction getting stronger = carb getting choked.

Everything I'm about to write is pure speculation, as I have no expertise in aviation and more specifically the Ford Trimotor, other than having visited the KingsfordSmith museum at Brisbane airport a number of times :-). Anyhow, my guess would be on the Trimotor, there's probably two things:

As mentioned by other answers, there's technical issues to do with remote mounting the guages due to 1920s tech.
Maybe the engines have manual mixture control and for that reason, manifold pressure is relatively important for adjusting engine operation. I would also speculate that given you have a tachometer etc for the front engine, the pilot can easily tell if throttles need adjusting for the wing mounted engines, once the mixtures have been adjusted due to the audible beat frequencies that occur if the engines are "out of sync".


text:
Would the "Calibrated Altitude" figure on FlightRadar24 better be labelled "Pressure Altitude"?

On FlightRadar24, when a user clicks on an airplane icon, the data panel shown above is displayed.  Note the figure labelled "calibrated altitude".
For an airplane flying below the "transition altitude" (18,000' in the US), would this value better be labelled "pressure altitude" in most cases?
Meaning that this is the figure that we'd see on a barometric altimeter with the Kollsman window set to 29.92 inches Hg (or 1013.2 milli-bars)?  And meaning that a correction for the altimeter setting at a nearby station should be applied to get the MSL value that the pilot would actually be seeing on the aircraft's barometric altimeter?
Relevant to this question, would be the following questions:
a) Is the figure called "calibrated altitude" on the FlightRadar24 data panel based on data from the aircraft's ADS-B transponder?
b) Does the aircraft's ADS-B transponder always transmit "pressure altitude", with no correction for non-standard meteorological conditions?
c) If the answers to "a" and "b" are both "yes", then does FlightRadar24 apply any correction for non-standard meteorological conditions, based on the altimeter setting values for nearby stations, to this data?
(Other ASE answers to related questions seem to have established that the answers to (a) and (b) are both "yes" -- so it seems that (c) is the crucial unresolved question.)
It would seem that if the answers to these questions were "yes", "yes", and "no", respectively, then the value titled "calibrated altitude" would indeed be better titled "pressure altitude".  Is this in fact the actual situation?  Does FlightRadar24 in fact not apply any correction to the received altitude data, to compensate for non-standard meteorological conditions, where the correct altimeter setting for the area is other than 29.92 inches Hg (1013.2 millibars)?

Relevant: https://www.flightradar24.com/blog/understanding-extended-mode-s-data-in-flightradar24/ , https://mooneyspace.com/topic/24268-ads-b-altitude-on-flightaware/page/2/, https://discussions.flightaware.com/t/general-confusion-about-aircraft-ads-b-altitude/79557 , https://www.aopa.org/news-and-media/all-news/1998/may/flight-training-magazine/form-and-function#:~:text=Encoded%20with%20a%20transponder%27s%20return,pressure%20altitude%20to%20indicated%20altitude ,

Content in chat rooms (some of which were originally comments under the question or answer) created for this related question will be of interest here -- https://aviation.stackexchange.com/q/93337/34686, https://chat.stackexchange.com/rooms/136652/discussion-on-answer-by-helpinghand-how-low-was-this-kc-135-near-kiab , https://chat.stackexchange.com/rooms/136614/discussion-between-vikki-and-helpinghand .

These ASE questions are somewhat related -- https://aviation.stackexchange.com/q/37654/34686, https://aviation.stackexchange.com/q/53211/34686, https://aviation.stackexchange.com/q/46879/34686

To my knowledge, "yes/yes/no" is correct, and therefore saying that the altitude is "calibrated" would be misleading to the point of falsehood. But I don't work for FR24 and thus I can't say for sure.

Additional relevant ASE Q or A: https://aviation.stackexchange.com/a/45261/34686, https://aviation.stackexchange.com/q/3529/34686, https://aviation.stackexchange.com/a/52542/34686, https://aviation.stackexchange.com/a/45902/34686

FlightRadar24 gets aircraft data from multiple sources: ADSB is primary (terrestrial and satellite), other are MLAT (mode S xpdr triangulation), Radar (xpdr alitude), Open Glider Network (aggregate of multiple sources) and WAGs (position estimate when destination is known).
The data transmitted via ADSB is barometric pressure altitude, as is data via XPDR.
FlightRadar24's definition of altitude is as reported by the aircraft:

Altitude
For each flight tracked on Flightradar24 the calibrated altitude reported from the aircraft, which is a pressure-derived value, is displayed. Extended Mode S Data received from some aircraft also includes the GPS-derived altitude of the aircraft.

Their description of "how flight tracking works" also describes no corrections to any of the data received.
So the calibrated altitude displayed is pressure altitude, from multiple sources.


text:
"In the turn coordinator, the gyro is canted 30 degrees from the horizontal so it responds to roll as well as yaw"
According to Wikipedia, "In the turn coordinator, the gyro is canted 30 degrees from the horizontal, so it responds to roll as well as yaw." I don't understand this point. How does rotating the gimbal 30 degrees allow the turn coordinator to respond to roll? The angular momentum and torque vectors are the same in both situations. In this case, angular moment is pointed out of the screen and torque from rolling the aircraft pointed horizontal to the right. What am I missing?

I'm not sure the graphic is correct.   Assuming we are looking along the axis of the gyro (which is parallel to the wing), then roll torque would be up or down, and the arrows would show the precessional tendency (which would be blocked in the first and allowed in the second).

According to the right-hand rule, curl your fingers in the direction of rotation and your thumb points in the direction of the torque vector. https://www.pasco.com/products/guides/right-hand-rule

@marshmellow -- worked most of comments above into a re-work of answer, deleting those.  Would appreciate your editing question to add a note "own work" under the diagram, or else to note the source of it, thanks.

@BowlOfRed -- actually I now agree with you.  See  recent edit to answer.

Possible duplicate of https://aviation.stackexchange.com/questions/89060/why-is-the-turn-coordinator-gyro-tilted?noredirect=1&lq=1 , except that the present question seems to invite us to explain what is wrong with the diagram provided.

Short answer:

What am I missing?

In two words: gyroscopic precession.

The angular momentum and torque vectors are the same in both
situations.

Yes they are, but the orientation of the instrument's gimbal axis is not the same in each case, so the indication of the instrument will not be the same in each case.
In more detail:
In analyses like these, it is always useful to "take it to the extreme".
Consider two hypothetical cases:
One, the gimbal axis is purely "fore-and-aft" in the aircraft's reference frame.
And two, the gimbal axis is purely "up-and-down" in the aircraft's reference frame.
In both cases the gimbal axis is perpendicular to the spin axis of the gyro wheel.
So if one case makes the instrument respond only to yaw, then the other case must make the instrument respond only to roll.  And intermediate cases where the gimbal axis is somewhere between "fore-and-aft" and "up-and-down" in the aircraft's reference frame, must make the instrument respond to both yaw and roll.
(The instrument will not respond to pitch in any of these cases, because pitching motions are in the same plane of rotation as the gyro wheel's rotation about its axle.)
Seen in this light, we can boil your question down to the following: "If the gimbal axis were purely "up-and-down" in the aircraft's reference frame, why would the instrument respond to rolling motions of the aircraft, but not to yawing motions of the aircraft?"
When the aircraft rolls to the right, this exerts a downward force on the right-hand side of the gyro wheel and an upward force on the left-hand side of the gyro wheel.
Rotate these forces 90 degrees in the direction of the gyro's spin, as we always must when considering how a gyro wheel reacts to torque1, and we have an apparent forward force on one side of the gyro wheel and an apparent aftwards force on the other side of the gyro wheel.2  In other words the gyro wheel will experience an apparent yaw torque. This will make the gyro wheel pivot around the "up-and-down" gimbal axis.  Yawing the aircraft, on the other hand, will create a forward force on one side of the gyro wheel and an aftwards force on the other side of the gyro wheel, so the gyro will experience an apparent upward force on one side of the gyro wheel and an apparent downward force on the other side of the gyro wheel.3 In other words the gyro wheel will experience an apparent roll torque.  In this hypothetical case where the gimbal axis is purely vertical, this apparent yaw torque experienced by the gyro wheel cannot result in any rotation around the gimbal axis, so the instrument does not respond to yaw rotation of the aircraft.
Regarding the diagrams included in the question--
The diagram appears to be the question author's own work, and makes use of the right-hand rule convention for illustrating a torque or an angular momentum as a single vector.  We'll assume that the gyro's gimbal axis is parallel to the red bar in each diagram, which indicates that the aircraft's nose is toward the right side of each diagram, and we're viewing each diagram from somewhere out beyond the aircraft's right wingtip.  The blue dot labelled "angular momentum" represents a vector coming straight out of the page or screen toward the viewer, which illustrates that the gyro wheel is spinning counterclockwise as seen from our vantage point, i.e. with the top side moving toward the pilot and the bottom side moving away from the pilot.  By the right-hand rule convention, the direction of the roll torque illustrated by the single vector pointing toward the right side of the diagram, is toward the right (i.e. clockwise) in the aircraft's reference frame.  If this is meant to illustrate the apparent roll torque experienced by the gyro wheel after taking into account the gyroscopic precession effect, then it is clear that tilting the gimbal axis (parallel to the red bar) toward the vertical does not make the gyro sensitive toward this apparent roll torque-- rather, it makes the gyro less sensitive to this apparent roll torque.  But remember that, as explained above, an apparent roll torque on the gyro wheel is actually the result of a yawing motion of the aircraft.  If we want to illustrate the result of a rolling motion of the aircraft, we need to remember that this will make the gyro wheel experience an apparent yaw torque.  By the right-hand rule convention, we should illustrated this apparent yaw torque as an arrow pointing straight up or down, not forward or aft.  The diagram as drawn illustrates the apparent right roll torque exerted on the gyro wheel by a right yawing motion of the aircraft.  That doesn't really help us understand how tilting the gimbal axis toward the vertical makes the instrument become sensitive to rolling motions of the aircraft.
Footnotes:

Due to the principal of torque-induced precession, also known as gyroscopic precession.

The direction of the apparent roll torque experienced by the gyro wheel when the aircraft yaws depends on the direction of spin of the gyro wheel.  In principle the instrument could be built with the gyro wheel spinning in either direction.  In practice there are pros and cons to each direction.  For reasons beyond the scope of the answer, the gyro wheels of turn rate indicators (where the gimbal axis is purely "fore-and-aft" in the aircraft's reference frame) and turn "coordinators" (where the gimbal axis is canted 30 to 40 degrees towards the "vertical" in the aircraft's reference frame) usually spin in opposite directions.  Read more about that in this answer to a related question on ASE.

The direction of the apparent yaw torque experienced by the gyro wheel when the aircraft rolls depends on the direction of spin of the gyro wheel.  See footnote 2 for more.

This answer assumes that the motion of the gyro wheel around the gimbal axis is very small, so that the gyro wheel essentially maintains a constant orientation relative to the aircraft. In practice the motion of the gyro wheel around the gimbal axis can be large enough to cause pitching motions of the aircraft no longer to be completely in the same plane of rotation of the gyro wheel itself, which will make the instrument respond to aircraft pitching motions to some degree. This can actually be useful-- for example in the case of a turn rate indicator, it can keep the gyro wheel... (ctd)

(ctd) ...in a more constant orientation w/r/t the earth, which allows the instrument to indicate something closer to the actual turn rate (and without the need for an airspeed-specific calibration) than would be the case if the instrument only measured yaw rate. (Good.) But it also causes "looping error". (Bad.) Instruments may be designed with stronger or weaker centering springs to simultaneously minimize or maximize both of these effects.  Explored in more detail here http://aviation.stackexchange.com/a/81919/34686. May eventually incorporate this comment into a footnote in answer.

"then it is clear that tilting the gimbal axis (parallel to the red bar) toward the vertical does not make the gyro sensitive toward this apparent roll torque--"  should read "then it is clear that tilting the gimbal axis (parallel to the red bar) toward the vertical does not make the instrument more sensitive toward this apparent roll torque--"

Sentence in footnote 2 beginning "For reasons beyond the scope of the answer" would better read "... all turn rate indicators are set up so that the top of the gyro wheel spins away from the pilot (direction of spin CW as viewed from right wingtip), but it appears that some, but not all, turn coordinators are set up to spin in the opposite direction, so that the top of the gyro wheel spins toward the pilot (direction of spin CCW as viewed from right wingtip).  Read more about that, and the likely consequences, in this answer to a related question on ASE...

Re "Yes they are, but the orientation of the instrument's gimbal axis is not the same in each case, so the indication of the instrument will not be the same in each case."-- Could be followed by "Furthermore, the direction of the apparent torque experienced by the gyro wheel as the aircraft rolls actually acts 90 degrees to the direction you've illustrated in your diagram."

Last sentence before section addressing the diagrams should better read (changes bolded) "In this hypothetical case where the gimbal axis is purely vertical, this apparent ROLL torque experienced by the gyro wheel cannot result in any rotation around the gimbal axis, so the instrument does not respond to yaw rotation of the aircraft."

Re 'The instrument will not respond to pitch in any of these cases" --strictly speaking it is more accurate to say a rotation that only involves pitch will not be indicated by the instrument.  Once we have a yaw rotation, or in the case of a turn "coordinator", either a yaw rot. or a roll rot., the gyro wheel rotates to some small degree around the gimbal axis which does cause the gyro to respond to pitch rotations as well.  (This will be more clear if you imagine a really extreme rotation around the gimbal axis, like near 90 degrees.)  This is the source of "looping error".  ... etc

In a few days I'll edit these comments into answer and delete them...


text:
In the US, will the tower likely think my aircraft has been hijacked if I taxi with the flaps down?
In the US, will the tower likely think my aircraft has been hijacked if I taxi with the flaps down?
Related:
Why are flaps retracted when an aircraft is parked on ground?
https://fsims.faa.gov/wdocs/orders/ps_orders/a_7110.49d.htm

Note that the second link is to a document dated 40 years ago, and the first link says "was" rather than "is". Lots & lots has changed since 1980, and quite frankly the idea that you've landed at your filed destination & need to covertly communicate that you've been hijacked so you can be met by... somebody... who assembles as you taxi to your assigned parking spot... is a little dubious.

Cecelia Cichan might have something to say about making the flaps a last-minute checklist item...

From reading the document, it seems like flaps were not used to communicate a hijacking at all, but rather as a signaling device to tell ATC whether armed intervention is requested after the general situation has already been established (note that retracting flaps after landing is also listed as a signal!).

will the tower likely think my aircraft has been hijacked if I taxi with the flaps down?

No.
For the twenty-some-odd years I owned my plane, I only taxied with the flaps down (for important operational reasons), even at towered airports, and not once had anyone think I was being hijacked.
Indeed, it would be quite disconcerting (to say the least) for ATC to treat any behavior or condition not officially designated for the purpose as a signal that the aircraft has been hijacked.
For many airplane types, there are of course good reason not to leave the flaps down while taxiing. But worrying that ATC will think you've been hijacked isn't one of them.

Also, if it was something that everyone knew as as unspoken secret code, then it would also stand to reason that this would be broadly distributed information, meaning hijackers would also be aware of this "un-secret secret", rendering it more or less useless.

@J...: reasonable point, but I'll also point out that there are signals to ATC to indicate a hijacking, and they are well-documented. A hijacker that did their homework would know that. Many security procedures work best when, as is often the case, the criminal does not do their homework. "Security through obscurity" isn't a great approach to rely on as the primary defense, but it does help in many real-world scenarios.

Well, yes, but in this case it also suffers from being wildly non-specific in the sense that a weird flap deployment could just be a rookie mistake or even a reasonable flight configuration for some number of edge-case scenarios.

@J...: yes, definitely so. Hence the note to that effect in my post. :)